Apparatus and methods for stent manufacture

ABSTRACT

Apparatus and methods for manufacture of bifurcated stents are disclosed. The apparatus can include a base having a first mount, a second mount and a third mount. The first mount, the second mount and the third mount can be configured to secure a first mandrel, a second mandrel and a third mandrel at positions relative to one another. The mandrels may be configured to receive two or more mono-tubular stents so that the stents or components of the stents may be secured to one another to form a bifurcated stent.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present inventions relates to medical devices and, moreparticularly, to apparatus and methods for manufacture of bifurcatedstents.

2. Background of the Related Art

Stents and similar implantable medical devices, collectively referred tohereinafter as stents, are generally radially expandable endoprostheses.They are typically used to obtain and maintain the patency of the bodypassageway while maintaining the integrity of the passageway. Stentshave provided doctors with a desirable alternative to the more invasivesurgeries historically required to open obstructed passageways withinthe body. With the tendency being to avoid invasive surgeries, their useand range of applications has steadily increased.

Stents are typically tubular devices. That is, they comprise a body orwall that defines a lumen. Stents are frequently made of a thin-walledmetallic or woven material and have a pattern of apertures, openings orholes defined around the circumference of the stent along most of itslength. Typically, the pattern of apertures, openings or holes isconfigured to permit the stent to move from a contracted to an expandedposition. Stents may be constructed from a variety of materials such asstainless steel, cobalt-chromium alloys, such as Elgiloy,nickel-titanium alloys, such as Nitinol, shape memory polymers, amongother materials. The materials are typically selected for theirbiocompatibility among other physical characteristics that may bedesirable for particular applications.

Stents are typically configured to be implanted translumenally andradially enlarged after being positioned within a lumen. They may beimplanted in a variety of bodily lumens or vessels such as within thevascular system, urinary tracts, bile ducts, etc. The stent may providea prosthetic intralumenal wall or wall support. Some stents areparticularly adapted to reinforce blood vessels and to preventrestenosis following angioplasty in the vascular system. In the case ofa stenosis, a stent may provide an unobstructed conduit for blood tomove through the stenotic region of the vessel. In other variations, astent may be used to treat an aneurysm by removing the pressure on aweakened part of an artery so as to reduce the risk of embolism, or ofthe natural artery wall bursting.

Stents may be formed in a variety of methods. In one exemplarymethodology, a stent may be formed by etching or cutting the stentpattern from a tube or section of stent material. In another exemplarymethodology, a sheet of stent material maybe cut or etched according toa desired stent pattern whereupon the sheet may be rolled or otherwiseformed into the desired tubular or bifurcated tubular shape of thestent. In yet another exemplary methodology, one or more wires orribbons of stent material may be braided or otherwise formed into adesired shape and pattern.

Early, stents typically shared the common design of being mono-tubular.These mono-tubular stents were suitable axial delivery and implantationwithin a bodily lumen. Recently, smaller stents have been utilized.These smaller stents have been inserted into coronary arteries after acoronary angioplasty procedure. Coronary angioplasty is a medicalprocedure used to treat blocked coronary arteries as an alternative to acoronary bypass operation. However, the need to manufacture thesesmaller stents has introduced a number of complications into stentmanufacture one of which is the need for greater precision in themanufacturing process. In one technique, stents are cut with laser beamsfrom small diameter tubes. As they are formed from small diameter tubes,laser cut stents manufactured from such processes have typically beenmono-tubular.

Within the vasculature however, it is not uncommon for stenoses to format any of a wide variety of vessel bifurcations. A bifurcation is anarea of the vasculature or other portion of the body where a first (orparent) vessel is bifurcated into two or more branch vessels.Bifurcations exist within the body in a wide variety of configurations,angles, and vessel diameters. Where a stenotic lesion or lesions form atsuch a bifurcation, the lesion(s) can affect only one of the vessels(i.e., either of the branch vessels or the parent vessel) two of thevessels, or all three vessels.

Unfortunately, mono-tubular stents are not optimal for use at abifurcation body passageway or about a side branch of a body passageway.When implanted, mono-tubular stents can shield side branches emanatingfrom a bodily lumen. In these cases, there is an increased risk ofclosure of one of the side branches or arm of the bifurcation and, at aminimum, the increased resistance to the movement of fluid through theobscured branch or arm. Thus, a need exists for bifurcated stents tosupport these areas. However, the manufacture of bifurcated stents canbe complicated and may introduce a number of variables that are notnecessarily considered when manufacturing mono-tubular stents. Thesecomplications can be exacerbated when the bifurcated stent is of arelatively small diameter. Accordingly, a need exists for apparatus andmethods for manufacture of bifurcated stents.

SUMMARY OF THE INVENTION

This Summary of the Invention capsulizes some of the claimed aspects ofthe present inventions. Additional details of aspects of the presentinventions and/or additional embodiments of the present inventions arefound in the Detailed Description of the Invention and associatedFigures. Apparatus and methods in accordance with the present inventionsmay satisfy one or more of the needs listed in the Background of theInvention and will in certain configurations provide additionalimprovements and advantages that will be recognized by those skilled inthe art upon review of the following Detailed Description of theInvention and associated Figures.

In one aspect, the present inventions may provide a fixture formanufacture of a bifurcated stent. The fixture may include a base havinga first mount, a second mount, and a third mount. The base may define alower surface adapted to be stably received on a work surface. A firstmandrel, a second mandrel and a third mandrel may be secured to thebase. The base may further define an orifice positioned about a centralpoint and extending through the base between the lower surface and anupper surface. Alternatively to defining an orifice positioned about acentral point, the base may define a cavity positioned about a centralpoint and extending into the upper surface of the base.

The first mandrel may be secured to the first mount at one of aplurality of desired positions along the first mandrel. The first mountmay define at least a first mandrel receiving passage in which the firstmandrel may be secured. The first mandrel may be slidably positionedwithin the first mandrel receiving passage. The first mandrel receivingpassage may define a first longitudinal axis. The second mandrel may besecured to the second mount at one of a plurality of desired positionsalong the second mandrel. The second mount may define at least a secondmandrel receiving passage in which the second mandrel may be secured.The second mandrel may be slidably positioned within the second mandrelreceiving passage. The second mandrel receiving passage may define asecond longitudinal axis. The third mandrel may be secured to the thirdmount at one of a plurality of desired positions along the thirdmandrel. The third mount may define at least a third mandrel receivingpassage in which the third mandrel may be secured. The third mandrel maybe slidably positioned within the third mandrel receiving passage. Thethird mandrel receiving passage may define a third longitudinal axis.The first longitudinal axis, the second longitudinal axis, and the thirdlongitudinal axis may intersect at a central point. Each of the firstmandrel, the second mandrel and the third mandrel can be securable in atleast one position that places the first tip of the first mandrel, thesecond tip of the second mandrel, and the third tip of the third mandreladjacent to one another.

A first set screw lumen may be defined by the first mount. The first setscrew lumen intersecting the first mandrel receiving passage. A firstset screw may be threadably received within the first set screw lumen tosecure the first mandrel relative to the base.

A second set screw lumen may be defined by the second mount. The secondset screw lumen intersecting the second mandrel receiving passage. Asecond set screw may be threadably received within the second set screwlumen to secure the second mandrel relative to the base.

A third set screw lumen may be defined by the third mount. The third setscrew lumen intersecting the third mandrel receiving passage. A thirdset screw may be threadably received within the third set screw lumen tosecure the third mandrel relative to the base.

The first mandrel receiving passage may include a first internal thread.The first internal thread may be configured to receive including a firstexternal thread defined on an outer surface of the first mandrel. Thefirst external thread of the first mandrel may be threadably receivedwithin the first internal thread of the first mandrel receiving passageto permit the rotational positioning of the first mandrel within thefirst mandrel receiving passage. A first knob may be secured to a firstouter end of the first mandrel to assist a user at gripping and/orrotating the first mandrel.

The second mandrel receiving passage may include a second internalthread. The second internal thread may be configured to receiveincluding a second external thread defined on an outer surface of thesecond mandrel. The second external thread of the second mandrel may bethreadably received within the second internal thread of the secondmandrel receiving passage to permit the rotational positioning of thesecond mandrel within the second mandrel receiving passage. A secondknob may be secured to a second outer end of the second mandrel toassist a user at gripping and/or rotating the second mandrel.

The third mandrel receiving passage may include a third internal thread.The third internal thread may be configured to receive including a thirdexternal thread defined on an outer surface of the third mandrel. Thethird external thread of the third mandrel may be threadably receivedwithin the third internal thread of the third mandrel receiving passageto permit the rotational positioning of the third mandrel within thethird mandrel receiving passage. A third knob may be secured to a thirdouter end of the third mandrel to assist a user at gripping and/orrotating the third mandrel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a side view of an embodiment of a laser weldingapparatus including a fixture in accordance with the present inventionspositioned on a work surface;

FIG. 2 illustrates a perspective view of an embodiment of a bifurcatedstent manufactured using apparatus in accordance with the presentinvention;

FIG. 3A illustrates a perspective view of an embodiment of a fixture inaccordance with the present invention;

FIG. 3B illustrates a top view of an embodiment of a fixture inaccordance with the present inventions similar to the embodiment of FIG.3A;

FIG. 3C illustrates a side view of an embodiment of a fixture inaccordance with the present inventions similar to the embodiment of FIG.3A;

FIG. 3D illustrates a cross-sectional side view of an embodiment of afixture in accordance with the present inventions similar to theembodiment of FIG. 3A;

FIG. 4A illustrates a perspective view of another embodiment of afixture in accordance with the present invention;

FIG. 4B illustrates a top view of an embodiment of a fixture inaccordance with the present inventions similar to the embodiment of FIG.4A;

FIG. 4C illustrates a side view of an embodiment of a fixture inaccordance with the present inventions similar to the embodiment of FIG.4A;

FIG. 4D illustrates a cross-sectional side view of an embodiment of afixture in accordance with the present inventions similar to theembodiment of FIG. 4A;

FIG. 5A illustrates a perspective view of yet another embodiment of afixture in accordance with the present invention;

FIG. 5B illustrates a top view of an embodiment of a fixture inaccordance with the present inventions similar to the embodiment of FIG.5A;

FIG. 5C illustrates a side view of an embodiment of a fixture inaccordance with the present inventions similar to the embodiment of FIG.5A; and

FIG. 6 illustrates a top view of mandrels of a fixture in accordancewith the present inventions positioning stents to be welded to oneanother.

All Figures are illustrated for ease of explanation of the basicteachings of the present invention only; the extensions of the Figureswith respect to number, position, relationship and dimensions of theparts to form the preferred embodiment will be explained or will bewithin the skill of the art after the following description has beenread and understood. Further, the exact dimensions and dimensionalproportions to conform to specific force, weight, strength, and similarrequirements will likewise be within the skill of the art after thefollowing description has been read and understood.

Where used in various Figures of the drawings, the same numeralsdesignate the same or similar parts. Furthermore, when the terms “top,”“bottom,” “right,” “left,” “forward,” “rear,” “first,” “second,”“inside,” “outside,” and similar terms are used, the terms should beunderstood to reference only the structure shown in the drawings andutilized only to facilitate describing the illustrated embodiments.Similarly, when the terms “proximal,” “distal,” and similar positionalterms are used, the terms should be understood to reference thestructures shown in the drawings as they will typically be implementedby a manufacturer of stents using apparatus and methods in accordancewith the present inventions.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates an exemplary laser welding apparatus 100 including afixture 10 in accordance with the present inventions positioned on awork surface 106. Laser welding apparatus 100 generally includes a lasergenerator 102 having a laser source and optical focusing mechanism. Thelaser generator 102 generates a laser beam 110. The laser beam 110 fromthe laser generator 102 is directed through the laser welding apparatus100 to a guide 104 which directs the laser beam through an aperture orlens 108 toward a target positioned on work surface 106. As illustrated,the laser beam 110 is directed downward in an orientation which issubstantially perpendicular to a plane defined by the work surface 106for exemplary purposes. A fixture 10 may be positioned on the worksurface 106 to secure one or more components of a bifurcated stent 210at a location that will permit the laser beam 110 to be directed at thedesired aspects of the bifurcated stent 210. Some components of abifurcated stent 210 are shown in FIGS. 2 and 6. The components includestents 212, 214, 216 which may be secured to fixture 10 for welding. Asillustrated for exemplary purposes, the fixture 10 securing the stents212, 214, 216 is positioned on work surface 106 so that the laser beammay be directed toward the location on or between one or more of stents212, 214, 216 be welded.

An embodiment and components of a bifurcated stent 210 manufacturedusing apparatus and methods in accordance with the present inventionsare generally illustrated in FIG. 2 for exemplary purposes. The elementsshown in FIG. 2 are provided solely for exemplary purposes and may beout of the proper proportions for particular stenting applications.These proportions have been selected for ease of illustration of theparticular elements. The bifurcated stent 210 may be particularlyconfigured for implantation in a blood vessel. In one aspect, thebifurcated stent 210 may be adapted to maintain the lumen of a bloodvessel in an open configuration. In one aspect, the bifurcated stent 210may be configured for use in a coronary angioplasty.

As particularly illustrated in FIG. 2, the bifurcated stent 210 ispositioned in a radially expanded configuration. As illustrated forexemplary purposes, the bifurcated stent 210 generally includes a firstmono-tubular stent 212, a second mono-tubular stent 214, and a thirdmono-tubular stent 216 welded to one another at a junction 230 by firstintraconnect 232, second intraconnect 234 and third intraconnect 236 ina generally radial arrangement. Each of the mono-tubular stents 212,214, 216 defines a passage 222, 224, 226. The first mono-tubular stent212 defines a first passage 222; the second mono-tubular stent 214defines a second passage 224; and the third mono-tubular stent 216defines a third passage 226.

The passages 222, 224, 226 generally extend between the proximal endsand distal ends and generally in a direction along the longitudinal axis242, 244, 246 of the respective mono-tubular stents 212, 214, 216. Thelongitudinal axis 242, 244, 246 have been illustrated as relativelypositioned during manufacture at 120 degree intervals about junction 30for exemplary purposes. Those skilled in the art will recognize that avariety of relative angles distinct from those illustrated may beadvantageous for various applications. Further, those skilled in the artmay recognize that the mono-tubular stents 212, 214, 216 do not have tobe fixed in a co-planar orientation relative to one another by thefixture 10. For example, the longitudinal axis 242 of first mono-tubularstent 212 manufactured at a 180 degree angle from the longitudinal axis44 of the second mono-tubular stent 214. In addition, the threemono-tubular stents 212, 214, 216 are illustrated as having beenmanufactured in a substantially co-planar configuration. Those skilledin the art will recognize that a bifurcated stent 210 may bemanufactured with a mono-tubular stent 212, for example, directedoutside the plane defined by the other two mono-tubular stents 214, 216without departing from the scope of the present inventions. Further,those skilled in the art will understand that one or more of themono-tubular stents 212, 214, 216 may include one or more curves alongits longitudinal axis which may have advantages in particularapplications. Further as illustrated, the mono-tubular stents 212, 214,216 are selected to be of generally equivalent in size and generalconfiguration only for exemplary purposes. Those skilled in the art willrecognize varying the diameter, length, cell patterns, or generalconfiguration may have advantages in particular applications. Forexample, the length and diameter for each of the stents may be optimizedfor both deliverability of the stent and vessel coverage for particularapplications.

Each of the illustrated stents 212, 214, 216 further includes one ormore intraconnects 232, 234, 236 at their proximal ends for exemplarypurposes. These intraconnects 232, 234, 236 may be used to interconnectthe stents 212, 214, 216 into a bifurcated stent 210. Such interconnectsare described in more detail in a U.S. patent application, entitledBifurcated Stenting Apparatus and Methods and assigned Ser. No.11/049,323 the disclosure of which is hereby incorporated by referencein its entirety. Those skilled in the art will recognize additionalstructures and configurations for stents or components thereof that mayutilize a fixture 10 in accordance with the present inventions in theirassembly into a bifurcated stent.

As particularly illustrated, each of the stents 212, 214, 216 includes apair of intraconnects 232, 234, 236 at their proximal ends for exemplarypurposes. For purposes of describing the elements and construction ofthe bifurcated stent 210, the term proximal shall refer to the end ofthe components adjacent to junction 230 and the term distal shall referto the end opposite the proximal end of each element. The first stent212 includes a first intraconnect 232, the second stent 214 includes asecond intraconnect 234, and the third stent 216 includes a thirdintraconnect 236. The intraconnects 232, 234, 236 are used to weld eachof the stents 212, 214, 216 relative to one another to form a bifurcatedstent 210. Intraconnects 232, 234, 236 are configured to be secured attheir distal ends to the proximal ends of the stents 212, 214, 216 andat their proximal ends to one another. Typically, the intraconnects 232,234, 236 are secured to one another by laser welding as is generallyillustrated throughout the figures for exemplary purposes. However, theintraconnects 232, 234, 236 may be welded using alternative methods,adhesively bonded or otherwise secured to one another using a fixture 10in accordance with the present inventions as will be understood by thoseskilled in the art upon review of the present disclosure.

Fixtures 10 in accordance with the present inventions generally includea base 12 relatively securing the position of at least two mounts 20,30, 40. A mandrel 22, 32, 42 is secured within each of the mounts 20,30, 40. The mounts 20, 30, 40 secure the relatively position at leasttwo mandrels 22, 32, 42 to permit components of a bifurcated stent 210to be precisely positioned and secured relative to one another. Fixtures10 in accordance with the present inventions may facilitate manufactureof bifurcated stent 210 by permitting the precision assembly of threeindependently fabricated mono-tubular stents 212, 214, 216. Themanufacture of a bifurcated stent 210 from two or more mono-tubularstents 212, 214, 216 can allow for the use of conventional mono-tubularstent manufacturing techniques to provide the precursors of a bifurcatedstent 210. This can reduce the need for special or complex toolingtypically required for manufacture and/or assembly of bifurcated stents.Embodiments and components of embodiments of fixtures 10 and methods inaccordance with the present inventions are generally illustrated inFIGS. 1 and 3A to 6.

The present inventions are generally described with reference to thefigures wherein the same numbers indicate similar, identical oranalogous elements in different figures and within individual figures.The elements identified in the figures may be drawn out of the properproportions for particular applications. However, these proportions havebeen selected for ease of illustration and description. Further, thefigures are intended to be illustrative rather than limiting and areincluded to facilitate the explanation of the apparatus of the presentinventions not to limit the scope of the claims.

Exemplary embodiments of fixtures 10 in accordance with the presentinventions are generally illustrated in FIGS. 1 and 3A to 6. Inaccordance with the present inventions, fixtures 10 are generallyconfigured to position two or more mono-tubular stents 212, 214, 216.The two or more mono-tubular stents 212, 214, 216 may be positionedrelative to one another to permit the mono-tubular stents 212, 214, 216to be secured to one another by techniques such as laser welding,adhesive bonding, among other techniques. As illustrated, the fixture 10generally includes a first mandrel 22, a second mandrel 32, and a thirdmandrel 42 over which one or more mono-tubular stents 212, 214, 216 maybe secured. The mandrels 22, 32, 42 are secured to a base 12 to properlyposition the stents 22, 32, 42 relative to one another.

The base 12 may be modular or a unitary component. The base 12 istypically sized to be easily handled and to permit its positioning on awork surface 106 of a laser welding apparatus 100. The base 12 includesa lower surface 14 configured to stably support the base 12 when thebase is positioned on a work surface 106 as shown in FIG. 1. In oneaspect, the lower surface 14 may be substantially planar to permit thebase to stably rest on a flat surface. In another aspect, the lowersurface 14 may define one or more feet or extensions upon which the base12 may rest or which may be secured to the laser welding apparatus 100.As illustrated, a first mount 20, a second mount 30 and a third mount 40may be secured to or may be integral with the base 12. One or more ofthe mounts 20, 30, 40 are configured to secure one or more of the firstmandrel 22, the second mandrel 32 and/or the third mandrel 42 at fixedpositions relative to one another and/or the base 12.

The first mount 20, the second mount 30 and the third mount 40 may beintegral with the base 12 or may be secured to a surface such as forexample an upper surface 16 of the base 12. In one aspect, one or moreof the mounts 20, 30, 40 may be formed within the base 12. In anotheraspect, one or more of the mounts 20, 30, 40 may extend upward from anupper surface 16 of the base 12. Mounts 20, 30, 40 may be secured tobase 12 with bolts 50 or may otherwise be secured to the base such as byadhesives or welding for example as will be recognized by those skilledin the art. The base 12 may define an orifice 18 extending through thebase between the lower surface 14 and the upper surface 16.Alternatively, the base may define a cavity 19 formed in the uppersurface 16 of the base 12.

Each of mandrels 22, 32, 42 is generally configured to be receivedthrough a passage 222, 224, 226 in one of the mono-tubular stents 212,214, 216. Mandrels 22, 32, 42 are typically configured in the form ofrods having a generally circular cross-section although otherconfigurations may be utilized as will be recognized by those skilled inthe art. Typically, mandrels 22, 32, 42 are generally illustrated aslinear however, the mandrels may have one or more curves or bends aswill be recognized by those skilled in the art upon review of thepresent disclosure. Mandrels 22, 32, 42 are oriented such that therelongitudinal axes are generally aligned with a central point 300 topermit the alignment and securing of aspects of mono-tubular stents 212,214, 216 adjacent to one another. In one aspect, the central point 300may be aligned with the central axis of a circular orifice 18 or cavity19. First mandrel 22, second mandrel 32, and third mandrel 42 aretypically secured to the base 12 to allow the first tip 28, second tip38 and third tip 49 to be positioned adjacent to one another. Dependingon the embodiment, tips 28, 38, 48 may be blunt, rounded or in the formof a point or edge or otherwise configured as will be recognized bythose skilled in the art. In certain aspects, first mandrel 22, secondmandrel 32, and third mandrel 42 may be secured to the base 12 to allowthe first tip 28, second tip 38 and third tip 49 of the respectivemandrels 22, 32, 42 to be abutted against one another. A first knob 62,second knob 72 and a third knob 82 may be positioned at the respectivefirst outer end of the first mandrel 22, the second outer end of thesecond mandrel 32, and the third outer end of the third mandrel 42,respectively. Knobs 62, 72, 82 may include ridges or cavities to accepttools to simplify the manipulation of the mandrels 22, 32, 42 by a user.

As is generally illustrated for exemplary purposes, first mandrel 22,second mandrel 32, and third mandrel 42 may be received through a firstmandrel receiving passage 66, a second mandrel receiving passage 76 anda third mandrel receiving passage 86, respectively. The first mandrelreceiving passage 66, second mandrel receiving passage 76 and thirdmandrel receiving passage 86 can be defined in base 12 and/or by firstmount 20, second mount 30 and third mount 40, respectively. Typically,the mandrel receiving passage 66, 76, 86 will fix the angular positionof each of first mandrel 22, second mandrel 32, and third mandrel 42relative to the base 12. The first mandrel 22, second mandrel 32, andthird mandrel 42 may be relatively sized to slide through first mandrelreceiving passage 66, second mandrel receiving passage 76 and thirdmandrel receiving passage 86, respectively. In one aspect, the base 12may further define a first set screw lumen 25, a second set screw lumen35 and a third set screw lumen 45 in communication with first mandrelreceiving passage 66, second mandrel receiving passage 76 and thirdmandrel receiving passage 86, respectively. A first set screw 24, asecond set screw 34 and a third set screw 44 may be threadably engagedwithin first set screw lumen 25, second set screw lumen 35 and third setscrew lumen 45 to lock the first mandrel 22, second mandrel 32 and thirdmandrel 42 at desired positions. To lock a mandrel 22, 32, 42 at adesired position, a set screw 24, 34, 44 may be rotated relative to thebase within the set screw lumen 25, 35, 45 to bias an end of the setscrew 24, 34, 44 against the mandrel 22, 32, 42. In another aspect,first mandrel receiving passage 66, second mandrel receiving passage 76and third mandrel receiving passage 86 may include first internal thread65, second internal thread 75, and third internal thread 85,respectively. When the mandrel receiving passage 66, 76, 86 includeinternal thread 65, 75, 85, first mandrel 22, second mandrel 32, andthird mandrel 42 may include first external thread 64, second externalthread 74, and third external thread 84 respectively, to engage internalthread 65, 75, 85. When external thread 64, 74, 84 are engaged withexternal thread 65, 75, 85, the respective mandrel 22, 32, 42 may belongitudinally positioned relative to base 12 by rotating the mandrel22, 32, 42.

FIGS. 3A to 3D illustrate similar exemplary embodiments of a fixture 10in accordance with one or more of the present inventions. Asillustrated, the base 12 is a modular component including a first mount20, a second mount 30 and a third mount 40 extending from an uppersurface 16 of base 12. The first mount 20, second, mount 30 and thirdmount 40 are secured to the upper surface 16 of the base 12 with bolts50 which extend through the mounts 20, 30, 40 into base 12. Asillustrated, the first mount 20, second mount 30 and third mount 40include a first channel 26, a second channel 36 and a third channel 46,respectively on an upper surface of the mount. The first channel 26,second channel 36, and third channel 46 extend in a substantiallyparallel orientation with the first mandrel receiving passage 66, secondmandrel receiving passage 76 and third mandrel receiving passage 86,respectively. The first channel 26, second channel 36, and third channel46 may include a first biasing member 126, a second biasing member 136and a third biasing member 138 which may be in contact with a firstmandrel 22, a second mandrel 32 and a third mandrel 42, respectively.The biasing members 126, 136, 146 may inhibit unwanted movement ofassociated mandrels 22, 32, 42 within mounts 20, 30, 40. As illustratedin FIGS. 3A to 3D, the base 12 includes a lower surface of base 12 isflat to permit base 12 to be stably rested on a flat work surface suchas work surface 106, shown in FIG. 1. Further, the base 12 defines anorifice 18 extending through the base 12 between the lower surface 14and the upper surface 16. The orifice 18 may permit the welding ofmono-tubular stents 212, 214, 216 when either the lower surface 14 orthe upper surface is placed adjacent to a work surface 106 of a laserwelding apparatus 100. Thus, the orifice 18 may permit the fixture 10mono-tubular stents 212, 214, 216 to be secured to one another onopposing sides without requiring that the removal of the mono-tubularstents 212, 214, 216 from their respective mandrels 20, 30, 40.

Mandrels 22, 32, 42 are illustrated in FIGS. 3A to 3D as linear rods.The first mandrel 22, second mandrel 32, and third mandrel 42 arereceived through a first mandrel receiving passage 66, a second mandrelreceiving passage 76 and a third mandrel receiving passage 86,respectively. The mandrels 22, 32, 42 are illustrated as slidablypositioned within mandrel receiving passage 66, 76, 86. Fixture 10 ofFIGS. 3A to 3D uses set screws 24, 34, 44 to lock the mandrels indesired positions. Mandrels 22, 32, 42 shown as oriented to align theirlongitudinal axes with central point 300. The central point 300 isillustrated as generally aligned with the central axis of orifice 18.First mandrel 22, second mandrel 32, and third mandrel 42 are secured tothe base 12 to allow the first tip 28, second tip 38 and third tip 49 tobe positioned adjacent to one another. If desired by a user of theillustrated embodiment, first mandrel 22, second mandrel 32, and thirdmandrel 42 may be positioned with the first tip 28, second tip 38 andthird tip 49 abutted against one another. Accordingly, aspects ofmono-tubular stent 212, 214, 216 positioned about the mandrels 22, 32,42 may be properly positioned for laser welding or other techniques usedto secure such aspects.

FIGS. 4A to 4D illustrate another set of similar exemplary embodimentsof a fixture 10 in accordance with the present inventions. Asillustrated, the base 12 is a unitary component without distinct mounts20, 30, 40. As illustrated, the base 12 includes a lower surface of base12 is flat to permit base 12 to be stably rested on a flat work surfacesuch as work surface 106, shown in FIG. 1. Further, the base 12 definesan orifice 18 extending through the base 12 between the lower surface 14and the upper surface 16. Similar to the embodiments illustrated inFIGS. 3A to 3B, the orifice 18 may permit the welding of mono-tubularstents 212, 214, 216 when either the lower surface 14 or the uppersurface is placed adjacent to a work surface 106 of a laser weldingapparatus 100. In addition, the base 12 of FIGS. 4A to 4D include afirst lateral passage 60, a second lateral passage 70, and a thirdlateral passage 80. First lateral passage 60, second lateral passage 70,and third lateral passage 80 extend about the longitudinal axisextending from the third mandrel receiving passage 86, the first mandrelreceiving passage 66, and the second mandrel receiving passage 76,respectively. The first lateral passage 60, second lateral passage 70,and third lateral passage 80 may permit the passage of a laser apparatus100 or laser beam 110. Accordingly, another portion of the mono-tubularstents 212, 214, 216 may be welded without removal of the mono-tubularstents 212, 214, 216 from fixture 10. The first mandrel receivingpassage 66, a second mandrel receiving passage 76 and a third mandrelreceiving passage 86 are radially spaced about a central point 300positioned within the approximate center of the orifice 18. Forexemplary purposes, the mandrel receiving passage 66, 76, 86 areoriented with their longitudinal axis at approximately 120 degree anglesfrom one another for exemplary purposes.

The embodiment of fixture 10 illustrated in FIGS. 4A to 4D includesinternal thread 65, 75, 85 positioned within first mandrel receivingpassage 66, second mandrel receiving passage 76 and third mandrelreceiving passage 86 to lock the mandrels in desired positions.Accordingly, the mandrels 22, 32, 42 are illustrated as linear rodshaving external thread 64, 74, 84 received by internal thread 65, 75,85. Accordingly, first mandrel 22, second mandrel 32, and third mandrel42 are positioned relative to the base by rotation. In one aspect, thefirst mandrel 22, second mandrel 32, and third mandrel 42 may be rotatedby rotation of a first knob 62, a second knob 72 and a third knob 82secured to the outer end of the respective mandrel 22, 32, 42. Mandrels22, 32, 42 are again secured to the base 12 to allow the first tip 28,second tip 38 and third tip 49 to be positioned adjacent to one another.If desired by a user of the illustrated embodiment, first mandrel 22,second mandrel 32, and third mandrel 42 may be positioned with the firsttip 28, second tip 38 and third tip 49 abutted against one another.Accordingly, aspects of mono-tubular stent 212, 214, 216 positionedabout the mandrels 22, 32, 42 may be properly positioned for laserwelding or other techniques used to secure such aspects.

FIGS. 5A to 5C illustrate yet another exemplary embodiment of a fixture10 in accordance with the present inventions. The fixture 10 asillustrated in FIGS. 5A to 5C is generally similar to the embodiment offixture 10 illustrated in FIGS. 3A to 3D with the addition of a platform92 upon which the base 12 is secured. The platform 92 defines an upperplatform surface 96 which is configured to stably receive the base 12.As particularly illustrated, the upper platform surface 96 is configuredto abut a lower surface 14 of the base 12. The upper platform surface 96may be configured to receive an upper surface 16 of the base 12. Aplurality of detents 95, 97, 99 may be provided on the upper platformsurface 96 to maintain the base 12 in a desired position on the upperplatform surface 96. The detents 95, 97, 99 may extend upward from theupper platform surface 96. In one aspect, the detents 95, 97, 99 arerelatively positioned to abut a peripheral portion of the base 12 tostably secure the base 12 to the platform 92. As particularlyillustrated, detents 95, 97, 99 may permit the base 12 to be secured tothe platform 92 in one of three relative positions. The relativepositions may be adjusted by lifting the base 12 from in between detents95, 97, 99 and rotating the base 12 in 120 degree relative to theplatform 92 before repositioning the base 12 between detents 95, 97, 99.In addition, a focusing aid 93 may be provided and positioned adjacentto the tips 28, 38, 48 of mandrels 22, 32, 42 to aid in the positioningof the laser apparatus 100 relative to fixture 10. The focusing aid 93may be in the form of a rod extending upward from the platform 92 or, inother aspects, from the base 12 to position an upper surface 97 of therod adjacent to the tips 28, 38, 48 of mandrels 22, 32, 42. Such afocusing aid 93 may assist in focusing the optics by better facilitatinga determination of the focal position of the laser relative to theworkpiece.

A fixture 10 in accordance with the present inventions may be used tomanufacture a bifurcated stent 210 from mono-tubular stents 212, 214,216 using a range of techniques as will be recognized by those skilledin the art upon review of the present disclosure. Generally, the eachmono-tubular stent 212, 214, 216 may be made by laser cutting, water-jetcutting, or chemical etching of a preformed tube or a sheet to be rolledinto a tube; by molding; by weaving; or by other methods that will berecognized by those skilled in the art. In one exemplary method, themono-tubular stent 212, 214, 216 can be cut from a tube. In this method,the mono-tubular stent 212, 214, 216 is generally formed by removal ofmaterial from the cylindrical wall of the tube. The material remainingtypically forms the mono-tubular stent 212, 214, 216. Exemplaryapparatus and methods for manufacturing mono-tubular stents 212, 214,216 in accordance with the present inventions are disclosed in U.S. Pat.Nos. 5,324,913, 5,852,277 and 6,1214,653, the disclosures of which arehereby incorporated by reference. After cutting, the cut mono-tubularstent 212, 214, 216 is typically cleaned to remove the laser scale. Thiscleaning may be accomplished using chemicals and methods that are knownto those skilled in the art. The mono-tubular stents 212, 214, 216 maythen be heat treated in an annealing process to 1850 degrees Fahrenheitfollowed by cooling with nitrogen to a temperature of about 100 degreesFahrenheit before removing from the furnace. In one aspect, threemono-tubular stents 212, 214, 216 may be laser welded together. Torelatively position mono-tubular stents 212, 214, 216, each of themono-tubular stents 212, 214, 216 is fitted over a mandrel 22, 32, 42 ofa fixture 10. The first tip 28, second tip 38 and third tip 38 of therespective mandrels 22, 32, 42 are then secured in a generally radialorientation about central point 300. The mono-tubular stents 212, 214,216 are positioned on the mandrels 22, 32, 42 such that their proximalends are positioned relative to one another in a manner to permit thelaser welding of aspects of proximal ends to one another. As illustratedfor exemplary purposes in FIG. 6, the aspects to be welded togetherinclude terminal connectors 262, 264, 266. The terminal connectors 262,264, 266 may then be laser welded at their first surfaces 272, 274, 276and/or second surfaces 282, 284, 286. Once welded or otherwise securedto one another, the mandrels 22, 32, 42 may be released from the baseand removed from their respective passages within the mono-tubularstents 212, 214, 216 to leave the substantially completed bifurcatedstent 210.

Although illustrated and described herein with reference to certainspecific embodiments, the present inventions is nevertheless notintended to be limited to the details provided in the foregoingdescription. Rather, various modifications may be made in the detailswithin the scope and range of equivalents of the claims and withoutdeparting from the spirit of the invention.

1. An apparatus for manufacture of a bifurcated stent, comprising: abase including a first mount, a second mount, and a third mount, thebase defining a lower surface adapted to be stably received on a worksurface, a first mandrel defining a first tip, the first mandrel securedto the first mount at one of a plurality of first desired positionsalong the first mandrel; a second mandrel defining a second tip, thesecond mandrel secured to the second mount at one of a plurality ofsecond desired positions along the second mandrel; a third mandreldefining a third tip, the third mandrel secured to the third mount atone of a plurality of third desired positions along the third mandrel;each of the first mandrel, the second mandrel and the third mandrelbeing securable in at least one position that places the first tip, thesecond tip, and the third tip adjacent to one another.
 2. An apparatus,as in claim 1, further comprising the first mount defining at least afirst mandrel receiving passage, the second mount defining at least asecond mandrel receiving passage and the third mount defining at least athird mandrel receiving passage, the first mandrel receiving passagedefining a first longitudinal axis, the second mandrel receiving passagedefining a second longitudinal axis and the third mandrel receivingpassage defining a third longitudinal axis, the first mandrel slidablypositioned within the first mandrel receiving passage, the secondmandrel slidably received within the second mandrel receiving passage,and the third mandrel slidably received in the third mandrel receivingpassage.
 3. An apparatus, as in claim 2, further comprising a first setscrew lumen intersecting the first mandrel receiving passage and a firstset screw threadably received within the first set screw lumen to securethe first mandrel relative to the base; a second set screw lumenintersecting the second mandrel receiving passage and a second set screwthreadably received within the second set screw lumen to secure thesecond mandrel relative to the base; and a third set screw lumenintersecting the third mandrel receiving passage and a third set screwthreadably received within the third set screw lumen to secure the thirdmandrel relative to the base.
 4. An apparatus, as in claim 2, furthercomprising the first longitudinal axis, the second longitudinal axis,and the third longitudinal axis intersecting at a central point.
 5. Anapparatus, as in claim 2, further comprising: the first mandrelreceiving passage including a first internal thread and the firstmandrel including a first external thread, the first external thread ofthe first mandrel threadably received within the first internal threadof the first mandrel receiving passage to permit the rotationalpositioning of the first mandrel within the first mandrel receivingpassage; the second mandrel receiving passage including a secondinternal thread and the second mandrel including a second externalthread, the second external thread of the second mandrel threadablyreceived within the second internal thread of the second mandrelreceiving passage to permit the rotational positioning of the secondmandrel within the second mandrel receiving passage; and the thirdmandrel receiving passage including a third internal thread and thethird mandrel including a third external thread, the third externalthread of the third mandrel threadably received within the thirdinternal thread of the third mandrel receiving passage to permit therotational positioning of the third mandrel within the third mandrelreceiving passage.
 6. An apparatus, as in claim 5, further comprising afirst knob secured to a first outer end of the first mandrel, a secondknob secured to a second outer end of the second mandrel, and a thirdknob secured to a third outer end of the third mandrel.
 7. An apparatus,as in claim 1, further comprising the base defining an orificepositioned about a central point and extending through the base betweenthe lower surface and an upper surface.
 8. An apparatus, as in claim 1,further comprising the base defining a cavity positioned about a centralpoint and extending into the upper surface of the base.